Jerry Seinfeld is reinventing himself – not that there’s anything wrong with that – as a born-again stand-up comic.

Trolling his home turf of the Upper West Side, the master of observational comedy is hitting the streets and the Starbucks at Columbus Avenue and 67th Street, looking for fresh material.

Most of his days are spent wandering up and down Broadway scribbling notes. He has even showed up, unannounced, to test out the material at the Gotham Comedy Club at 34 W. 22nd St. in Chelsea.

In his quest for new material, he visits Zabar’s Gourmet Foods on Broadway, Pomodoro’s restaurant on Columbus Avenue and cheese counters and diners. Watching, observing, trying to see the humor in the mundane.

“Jerry’s reinventing himself,” a source who knows him told The Post. “For the past year, he’s been flying all over the country, doing gigs in small towns and cities.

“He’s a simple guy, and in a lot of ways, Jerry’s doing a lot of the same stuff he’s always done. Hanging out, going for coffee, out for lunch. This is his bread and butter.”

For years, the star of the smash, self-titled NBC sitcom was a headliner in comedy clubs and one of the hottest acts in the country. Then, along came a television show about nothing. It’s nine-year run was a ratings bonanza, deeply ingraining Seinfeldisms into the popular lexicon.

After the show ended in 1998, the 48-year-old New Yorker disappeared into his marriage to Jessica Sklar and fatherhood. Now, a new documentary, “Comedian,” chronicles his often painful odyssey back to his roots.

The film is a warts-and-all look at Seinfeld’s return to the stage, and includes him facing hostile audiences in the hick towns of the hinterland, as well as his triumphant return to the big time – and big laughs. It opens Oct. 20 in New York.

“People never get to see what it takes to walk out on stage with a smile and have all these jokes,” he told “The Today Show.” “There’s a lot that goes into that.”

Seinfeld could have had his pick of projects – another series, a talk show, movies – but instead, he has returned to the sometimes unforgivable stage.

So far, his new act is getting rave reviews, and critics are sensing a new seriousness in the comic’s material. Seinfeld attributes the change to his 1999 marriage and the 2000 birth of his daughter, Sascha.

Both events are also new fodder for his stand-up act.

“At the end of the day, Jerry sees himself as a stand-up comic. He loves doing stand-up,” the source said. “How many projects has he turned down? He didn’t have to do this. He wants to do it. This is his first love.”

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BACK OF THE PROWL

Jerry Seinfeld has been collecting new comedic fodder at his local Starbucks at West 67th Street which he tested out in an unannounced visit to the Gotham Comedy Club.

ON UNEMPLOYMENT

“Can you believe the number of people who don’t have to be at work? What are all these people doing? Actually, this is a great intersection, 67th and Columbus. You’ve got ABC over there, Starbucks over here, a Reebok over there. It’s a perfect confluence of wasted time.”

ON LOW-RISE PANTS

“It’s a time-saving device. When you need to go to the bathroom, you are that much closer to having your pants off.”

ON BABIES

“Why would you want something in your life that stands in the middle of your living room, looks you in the eye and then poops in their pants? As they look at you! I tell you, it’s a little unnerving.”